Local authorities must ensure that land is kept free for primary and post-primary schools alongside new housing developments, the Minister for Education, Mr Dempsey, has said.
Speaking at the Fianna Fáil Ardfheis, he said the Department of Education is currently having to pay up to €1 million an acre for sites because land was not allocated in the past.
"A post-primary school needs 10 acres. Our money doesn't last very long," the Minister told Killarney delegate Mr Anthony Kelly during a debate last night.
Another delegate, Mr Ed O'Brien, said the Minister had to keep teachers' morale high during confrontations between the Department and teaching unions.
The Minister said he had repeatedly paid tribute to the contribution made by teachers. "We have been extremely fortunate in the men and women that we have attracted into the profession. I deplore cheap attacks on teachers from people who have never stood in the front of a classroom once in their lives. The role of teachers is critical."
He added: "I do not see it as my role just to be standing up for teachers, though that is important.
"There are other people in the system that have not the same voice, the same unions and the same clout. I have an obligation to parents and students as well."
Some 6,000 extra teachers are working in classrooms in comparison with 1997. This will see the pupil/teacher ratio fall to 17.5:1 later this year.
But resources must be targeted, Mr Dempsey said. "I don't think we can afford the luxury. I know we can't afford the luxury to reduce ratios right across the board.
"It isn't going to benefit those who need it most."
The Minister said pupil teacher ratios in disadvantaged areas now stand at 11:1, though money will be targeted this year onto the National Educational Psychological Service, guidance counsellors and truancy inspectors.
Urged by Dún Laoghaire delegate, Mr Brendan Kelly, to help cash-strapped schools, the Minister said €350 million will be spent this year on new school buildings. Some 14 sports halls will be built this year.
"However, I will not approve halls in any school unless, or until, I have a written guarantee that they will be open outside school hours," he declared.
On the problem of drink and drugs affecting young people, Mr Dempsey said a number of government Departments are co-operating.
Complaining about truancy rates, Dublin West delegate Ms Annie Holt said she had complained frequently about missing pupils, but nothing had happened.
Some 80 educational welfare officers have been appointed to check on attendance records, though the Minister said he wants them to co-operate fully with the 700 teachers caring for the most vulnerable pupils.
"I regret to say that we have not got a protocol agreed on this yet, but it isn't the fault of the Department of Education and Science," Mr Dempsey told Ms Holt.